1. Field of the Invention
The present invention relates to grout and lifting tubes of the type used for moving and placing concrete sections.
2. Description of the Related Art
Grout and lifting tubes are often used in the tunnel industry, for example, for moving and placing the large concrete sections that form the walls of tunnels. In one system, one or more such tubes are cast into each concrete segment, and a lift member is threaded into each tube. The lift member is grasped by a crane or other device to move the concrete section into place, followed by removing the lift member from the tube. Thereafter, grout is pumped through a non-return valve in the tube to the outside of the concrete section, and the grout cures to seal the exterior of the tunnel. Finally, caps are threaded into the open ends of the tube to close same.
The tube typically includes one or more hydrophilic O-rings fitted about its exterior surface to provide a seal between the tube and the surrounding concrete in order to prevent moisture infiltration into the interior of the tunnel. A disadvantage of using O-rings is that same are expensive, particularly when a number of O-rings are needed for each tube, and when the tunnel may include hundreds or even thousands of concrete sections and tubes. It is also thought that such O-rings could potentially not provide sufficient sealing in applications where the O-rings may be subjected to high hydrostatic pressure, such as in deep underground tunnels or underwater tunnels.
What is needed is a grout and lifting tube that is an improvement over the foregoing.